Although liquid crystal displaying apparatus and liquid crystal televisions have gradually become main products in a displaying area, effort for improving picture quality of liquid crystal display is continuous, wherein a main research focuses on how to increase contrast ratio (CR) of the liquid crystal displaying apparatus. Actually, the contrast ratio of the liquid crystal displaying apparatus is a ratio of luminance, that is, a ratio of the blackest luminance unit and the whitest luminance unit, and the brighter the white is and the darker the black is, the higher the contrast ratio is. Thus, the contrast ratio is an important parameter of the liquid crystal displaying apparatus. In case of a same luminance value, the higher the contrast ratio is, the more color layers can be displayed. At present, it is limited for the degree of increasing the contrast ratio by means of internal structures, materials, and manufacture processes of the liquid crystal displaying apparatus, and prior arts focus mainly on increasing the contrast ratio by a driving method.
Therefore, a prior art proposes a dynamic contrast ratio adjusting technique, and particularly a method for enabling the liquid crystal displaying apparatus to represent a bigger “bright-dark difference” according to a bright-dark ratio of a displayed picture. Said method differs from a method of calculating the contrast ratio according to black/white luminance of a still picture in performing a calculation by executing a luminance statistics of an input picture. For example, the prior art proposes a dynamic Gamma control (DGC) method, which firstly performs a histogram statistics on received low voltage differential signaling (LVDS) data, figures out data amounts of different gray groups, compares data amounts of respective gray groups with preset thresholds, and adjusts a luminance control parameter of a backlight source when the data amount of respective gray group varies. However, when using such a dynamic Gamma control method of the prior art, flickering phenomenon is obvious and picture quality is decreased.